Steerable stylet and manipulative handle assembly

ABSTRACT

A steerable stylet and manipulative handle assembly especially adapted for guiding the introduction of an endocardial pacing or cardioversion/defibrillation lead or a catheter to a desired location in a patient&#39;s cardiovascular system. The steerable stylet or catheter designed to be introduced into the lumen of a lead comprises an outer, elongated tubular member of a length sufficient to extend through the length of the lead or catheter from its proximal opening to the distal end thereof, a traction element or pull wire extending generally through the length of the tubular member and within its lumen except for a predetermined distance in the distal portion thereof, and a manipulative handle coupled to the proximal ends of the tubular member and wire which may be employed with one hand to both rotate the tubular member and impart a continuously variable curve in the distal portion thereof. The distal portion of the tubular member is especially configured to be either attached to or cooperate with the distal end of the pull wire so that proximally-directed traction applied by the handle to the wire causes the distal portion of the tubular member to bend. The distal portion of the tubular member is provided with openings to allow the wire to exit and re-enter the lumen of the tubular member in the distal portion so that traction applied to the wire bows the tubular member into a curve of desired radius.

This is a continuation of application Ser. No. 07/751,278 filed on Aug.28, 1992 now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wire guide or stylet assembly for theintroduction of medical catheters or electrical leads to a desired sitewithin the patient's body, and specifically to a steerable styletassembly for imparting a desired dynamic curvature in the distal portionof a catheter or lead during its introduction in order to guide itthrough curvature in the patient's vascular system and to a desired sitein the patient's cardiovascular system.

2. Description of the Prior Art

The marked advances in cardiac and vascular surgery in the past fewyears and other medical problems that require diagnostic study of thevascular beds and systems as well as the advances in pacing and cardioversion, has led to the extensive use of cardiac or vascular catheters,such as percutaneous transluminal coronary angioplasty (PTCA) cathetersand transvenous or endocardial pacing and cardioversion leads. Theinsertion of a relatively long catheter or lead body to an internal siterequires advancement of the catheter or lead into branch vessels atvarying angles relative to the feeding direction of the catheter or alead.

In respect to the introduction of PTCA catheters, for example, severaltechniques for introducing such catheters are available, including thecut-down method and the Seldinger techniques. The Seldinger techniqueinvolves surgically opening a vein or artery with a needle, inserting aguide wire into the vein or artery through the lumen of the needle,withdrawing the needle, inserting over the guide wire a dilator locatedinside an associated hemostasis valve and sheath, removing the dilatorand inserting a catheter through the hemostasis value and sheath intothe blood vessel. In this procedure, flexible spring wire guides of thetype disclosed in commonly assigned U.S. Pat. No. 4,815,478 toBuchbinder, et al, and the numerous patents referenced therein aresteered to the desired internal site by remotely deflecting the tip ofthe guide to facilitate movement of the guide wire around or through acurved path in the vessel. The steerable spring guide wire of the 478patent possesses a flexible tip constructed with flexible spring coilwire extending from the elongated guide wire body and coupled to a longtip which is additionally coupled to a deflection wire extending throughthe flexible tubing body and the spring coil as well as a control wireextending through the lumen provide for the deflection of the distal tipportion by the application of traction to the proximal end of thecontrol wire. The control wire remains within the confines of theelongated tubular body as well as the loosely-wound flexible spring coildistal portion thereof. As stated above, once the distal portion of theguide wire is advanced to the desired internal site, then the lumen ofthe tubular catheter is advanced over the guide wire until its distaltip is advanced to the desired internal site, whereupon the guide wireis withdrawn.

In the pacing and cardioversion context, it is well known to guide theinsertion and proper placement of an endocardial lead to a desiredinternal site in a chamber of the patient's heart or in a vessel, suchas the coronary sinus, through the use of a stiffening stylet insertedinto the lumen of the pacing or cardioversion lead. Generally speaking,it is highly desirable that pacing and cardioversion leads be soflexible through their length that they are capable of flexing with themovement of the heart and other muscular movement so as to avoid thefracture of the lead body due to its cumulative stressing. Thus, pacingand cardioversion leads are generally too limp to be advanced on theirown through the venus system to the desired internal site and it hasbeen commonplace for many years to employ thin wire stylets extendeddown the lumen of the lead to stiffen the entire assembly and to imparta desired degree of curvature of the tip of the lead body duringinsertion. To accomplish this desirable result, the solid inner styletwire is given a temporary bend or curvature near its distal end when itis outside the lumen by the physician. After insertion through thelumen, the curved distal portion facilitates movement of the distal tipof the lead into branch vessels at certain points as the lead isadvanced and thereafter assists in directing the lead tip to the desiredinternal site within the patient's heart or cardiovascular system.

It is also commonly known to employ a stylet to straighten an atrialpacing lead, which is provided with a permanent "J"-shaped bend tofacilitate both the positioning and the retention of the atrialelectrode in the patient's atrial appendage as taught, for example, inU.S. Pat. No. 4,136,703, issued to Wittkampf. Insertion of these"J"-shaped leads is greatly facilitated through the use of a straightsolid inner stylet which, in this case, straightens the bend normallyfixed within the distal end of the lead itself.

Such endocardial pacing and cardioversion leads typically comprise alength of coiled wire conductor formed around an axial lumen and encasedwithin a suitable insulating material, such as silicone rubber orpolyurethane, that is substantially inert to body fluids and tissues. Ahollow connector pin is attached coaxially to the lumen and electricallyto the proximal end of the conductor. An electrically conductiveelectrode at the distal end of the conductor is adapted to be placed incontact with the endocardium or within the coronary sinus of thepatient. When more than one length of separately-insulated coiled wireconductors is employed in modern pacing and cardioversion leads, eachcoiled wire conductor is wound coaxially around the centrally-disposedlumen which extends through the connector pin and the correspondinglengths of coiled wire conductors to the distal end of the lead body.The lumen receives the stiffening stylet of cylindrical wire forimparting stiffness and curvature to the distal portion of the lead bodyto facilitate its advancement through the venus system and to thedesired internal site. Further details of the construction and utilityof such endocardial pacing leads may be obtained and referenced to U.S.Pat. Nos. 4,506,680, 4,577,642, 4,606,118, and 4,711,281, allincorporated herein by reference.

Insertion of such endocardial pacing and cardioversion leads frequentlyrequires that the physician commence the introduction through a leadintroducer introduced into a vein through a skin puncture made at asmall angle to the vein. At the outset, the stylet may be left straightor provided with a certain degree of curvature to facilitate theintroduction into the vein and through the initial curvature thereof.Thereafter, and from time to time, as the physician directs the distaltip of the lead in a tortuous path leading to the right heart, it may benecessary to withdraw the stylet and either substitute a new stylet orimpart a different curvature to the distal portion of the stylet,reinsert it and advance the distal portion of the lead a bit furtheruntil another obstacle to advancement is encountered. It is undesirableto contaminate the lumen with blood during this process because dryingblood can form a strong adhesive bond between the stylet and the pacinglead, making stylet removal impossible and rendering the lead unusable.Moreover, the continual withdrawal and reintroduction of stylets is timeconsuming and offers the potential of damaging the lead in the process.

In order to avoid the withdrawal and reintroduction of stylets, variousapproaches have been proposed including those disclosed in commonlyassigned U.S. Pat. No. 4,381,013 to Dutcher and U.S. Pat. No. 4,677,990to Neubauer. The '013 patent is directed to the use of a two-piecestylet having an inner solid portion for enabling a shape to be impartedto the lead to facilitate introduction in the fashion as described aboveand an outer tubular portion which enables the transmission of torqueapplied by the implanting physician at the proximal end to betransmitted to a helical fixation means located at the distal end of thelead. The transmission of this torque allows the helical fixation meansto be screwed into the endocardial tissue. Thus the solid wire innerstylet operates in the same fashion as the conventional solid wirestylets described above.

The '990 patent discloses the combination of a removable styletstiffening wire and one or more threads having very low elasticity whichare coupled near the distal end of the lead or at selective locationsalong the lead body extending for a portion of the length of the leadwithin the lead lumen and for a further portion outside the lumen butwithin the sheath. With the stylet inserted, traction applied to theproximal portion of the thread or threads imparts a curvature into thelead body as the thread is pulled taut. The curvature is dictated by thelocations at which the thread or threads are directed in the spacebetween the outer insulation sheath and the coiled wire conductor. Toachieve easier bending, the stylet is described as having portions ofreduced thickness along its length in parallel with the location of thethreads passage outside the lumen.

The '990 patent addresses concerns raised by the conventional techniqueof withdrawing, imparting a new curve, and reinserting the stiffeningstylet during the implantation procedure.

The use of the separate thread and stylet in the '990 patent and thetwo-piece stylet of the '013 patent as well as the conventionalone-piece stylets usually require the physician to employ both hands inmanipulating the lead and stylet to advance and withdraw the stylet androtate the lead body in manipulating the advancement of the distalportion of the lead through the venus system or into particular desiredsites for lodging the electrodes. U.S. Pat. No. 3,452,740 to Muellerdiscloses a spring guide manipulator for imparting a curvature androtation in a spring guide by one-handed use of a manipulative handle.The spring guide wire includes the conventional inner straight wirecoupled to the distal end of the coiled wire of the distal portion ofthe spring wire guide. When the handle is attached to a guide wire and acatheter is fitted over the guide wire, it is reported that the handlemay be employed to both rotate the guide wire and catheter as well asplace a curve in the distal portion of the catheter.

Despite these advances in the guide wire and catheter prior art as wellas the pacing and cardioversion lead stylet prior art, a need remainsfor a simple, easy-to-use stylet or catheter guide wire assembly whichprovides a wide degree of dynamic curvature to the lead or catheterbeing advanced by the physician.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a simpleand easy-to-use stylet and manipulative handle assembly for imparting adynamic curvature to the distal portion of a catheter or lead during itsadvancement through a blood vessel.

It is a further object of the present invention to make such stylet andmanipulative handle assembly easy-to-use with one hand.

It is a still further object of the present invention to provide such astylet and handle assembly of the character stated which is simple indesign, rugged in construction and economical to manufacture.

These and other objects of the present invention are realized in astylet for the advancement of a catheter or a lead having a lumenextending therein between a proximal and distal thereof, wherein thestylet comprises an elongated tubular member having a proximal and adistal end, with at least one aperture located a predetermined distancefrom the distal end of said tubular member, a traction element or pullwire attached at the distal end of said tubular member and extendingloosely outside said lumen for said predetermined distance, through saidaperture and said lumen, and from the proximal end of the tubularmember; and a manipulative handle coupled to the proximal end of saidtubular member, the manipulative handle compromising body memberattached to said proximal end of said tubular member and receiving saidproximal end of said wire therewithin, a slide member adapted to slidealong said body member through manipulation thereof by the physician anda control lever pivotally attached to said body member, fixedly attachedto said pull wire and loosely coupled to said sliding member.

In the preferred embodiments thereof, the tubular member preferablypossesses a second aperture more distally located then the firstaperture, and the pull wire extends from the distal end of the tubularmember through the lumen, out the second aperture, alongside the outersurface of the tubular member and back within the lumen through thefirst aperture so that when traction is applied to the pull wire, ittends to cause the tubular member along the predetermined distance tobow outward and away from the taut pull wire lying outside the lumen.The pull wire may be fixedly attached to the distal tip of the tubularwire or it may be coupled to an enlarged member that is too large topass through the lumen of the tube and bears against the distal end whentraction is applied, but otherwise may allow the advancement of thedistal end of the pull wire beyond the distal end of the tubular member.

In further preferred embodiments of the present invention, thepredetermined distance along the tubular member may comprise either acut-out section or a flattened section of the tubular member between thefirst and second apertures therein.

In accordance with the practice of the present invention, the distalportion and length of the tubular member and pull wire stylet may beintroduced into the lumen of a lead or catheter and the proximal endthereof may be coupled to the housing of the handle assembly.Manipulation of the distal portion of the lead or catheter may beaccomplished by rotating the handle while advancing or retracting theslide member, thereby releasing or applying traction to the pull wireand straightening or curving the distal portion of the catheter or lead.

Advantageously, as traction is applied continuously the lever provides amechanical advantage of 2:1 or more between the force needed to pull thewire directly and the force needed to operate the slide. This reducesthe mechanical force to be applied by the fingers and also allows theslide member to be temporarily fixed in one location with theapplication of an external force. A continuous, dynamic range ofcurvature from zero to one hundred eighty degrees may be induced in thedistal portion of the lead or catheter. Lateral displacement of the pullwire outside the lumen of the tubular member is restrained by the lumenof the catheter or lead. Thus a very small movement of the slider inrelation to the/body of the manipulative handle causes a large change incurvature of the distal portion of the lead or catheter. The 2:1mechanical advantage of the lever expands this range of control motionof the slide member and allows for increased fineness of control of thestylet curvature.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, advantages and features of the invention willbecome more apparent and the invention will be more fully understood byreference to the drawings of the preferred embodiments thereof, wherein:

FIG. 1 is a perspective view illustrating the steerable stylet andmanipulative handle assembly of the present invention;

FIG. 2 is a side elevation view of the manipulative handle of thepresent invention depicting the slide member advanced distally thusstraightening the distal portion of the steerable stylet;

FIG. 3 is a side elevation view of the manipulative handle of thepresent invention with the slide member retracted proximally to applytraction to the pull wire and impart curvature to the distal portion ofthe stylet;

FIG. 4 is a perspective view of the housing of the manipulative handleshowing its internal and external configuration;

FIG. 5 is a perspective view of a spring clip inserted in a groove inthe housing of the manipulative handle;

FIG. 6 is a perspective view of the lever used in the housing of themanipulative handle;

FIG. 7 is a perspective view of the slide member of the manipulativehandle;

FIG. 8 is a top view of the first embodiment of the distal portion ofthe stylet of the present invention;

FIG. 9 is a cross-sectional view of the elongated tubular member andpull wire along lines A--A of FIG. 8;

FIG. 10 is a cross-sectional view of the elongated tubular member andwire taken along lines B--B of FIG. 8;

FIG. 11 is a cross-sectional view of a die and tool for flattening thepredetermined length of the distal portion of the tubular memberdepicted in FIG. 8;

FIG. 12 is a top view of a distal portion of a further embodiment of thesteerable stylet of the present invention;

FIG. 13 is a side view of the cut-out section of FIG. 12; and

FIG. 14 is an illustration of the dynamic curvature in the X-Y planeimparted by a prototype steerable stylet and manipulative handleassembly in accordance with the teachings of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As described above, the steerable stylet and manipulative handleassembly of the present invention may be advantageously employed ineither the introduction of a hollow tubular catheter, a sensor-bearinghollow tubular catheter or an intravascular electrical sensing and/orstimulation lead, such as a transvenous or endocardial pacing orcardioversion lead. The'specific catheters or leads are not illustratedor described except in reference to their cooperation with the styletand manipulative handle of the present invention.

Turning now to FIG. 1, it illustrates a perspective view of the styletand manipulative handle assembly of the present invention assembledtogether and illustrating a certain degree of curvature imparted in thedistal end thereof through retraction of the pull wire in relation tothe elongated tubular member.

The steerable stylet assembly illustrated in FIG. 1 comprises theelongated tubular member 10 and pull wire 12 having a proximal section14 and a distal section 16 with an elongated intermediate sectionextending therebetween (not specifically illustrated). The distalportion 16 possesses first and second apertures 18 and 20 separatedapart a predetermined distance. As described hereafter, thepredetermined distance including the distal straight section extendingbetween the second opening 20 and the distal tip 22 is preferably in therange of 2.5 to 4.0 inches. The radius of curvature to be imparted asthe pull wire 12 is retracted proximally is preferably between 0.50 and1.5 inches although other dimensions can also be used. In FIG. 1 a muchgreater radius of curvature is illustrated as very little traction isexerted on pull wire 12.

As depicted hereafter in conjunction with FIG. 8, the pull wire 12mechanically cooperates with the distal tip 22 of the tubular member 10and extends within the lumen 13 of the tubular member 10, out the secondopening 20 and alongside the tubular member 10 the predetermineddistance, whereupon it extends through the first opening 18 andproximally through the lumen 13 of the tubular member 10 to the proximalend 14. The pull wire 12 is only fixedly attached to the tubular member10 at the distal end 22, and, in certain embodiments, it may extenddistally from the distal end 22 and terminate in an enlarged elementhaving a diameter greater than the inside diameter of the lumen 13.

Turning now to the manipulative handle of the stylet assembly, itincludes the housing 30, the slidable member 32, the lever 34 and aspring wire clip element 36 which are attached to the proximal portion14 of the steerable stylet. In this regard, the tubular member 10 ismechanically attached to the opening in the neck-down portion 38 of thecylindrical housing 30 and terminates therewithin. The pull wire 10extends within the housing 30 to be coupled mechanically to the lever 34as illustrated more completely in FIGS. 2 and 3.

In use, the stylet tubular member 10 and pull wire 12 are inserted intothe connector pin opening of a lead which is axially arranged with thelumen within the lead body itself in the well-known fashion or into thelumen of a catheter. A press fit of the neck-down portion 38 with thelead connector pin opening or the catheter lumen opening is relied uponto hold the lead or catheter in fixed relation with the housing 30.After this mechanical connection is effected, the lead or catheter maybe rotated by rotation of the housing 30, and curvature may be impartedby the thumb engageable, slideable member 32 acting on the lever 34 andpull wire 10. The overall dimensions of the housing 30 and slide member32 are configured to fit within the physician's hand so as to allowthumb engagement with the circular ridge 40 to move the slideable member32 back and forth on housing 30 to increase or decrease the radius ofcurvature in the distal portion 16 of the stylet assembly. Frictionbetween the outer surface of the housing 30 and the inner surface ofslide member 32 is relied on to hold lever 34 in a desired position.

Turning now to FIGS. 2 and 3, side elevation, phantom line, views of themanipulative handle 28 in the relaxed and fully tractioned positions ofthe slideable member 32 and lever 34 in relation to housing 30 andcertain internal broken line components thereof are illustrated,respectively. Essentially, the lever 34 (depicted in FIG. 6) is pivotedat its fixed end 35 on wire clip 36, and its free end 37, captured byslot 44 in the top surface of slideable member 32, is pivoted back andforth by movement within an elongated channel 42 in housing 38. Theproximal end of pull wire 12 is fitted in an opening 39 along the bodyof the lever 34 so that it is pulled back and forth with movement of theslide element 32.

Turning now to FIG. 4, a perspective view of the housing 30 illustratesthe manner in which the lever 34 and the clip 36 are interconnected withthe proximal end of the pull wire. The lever 34, shown in FIG. 6, is aflat-sided elongated member have a pair of semicircular shaped ends 35and 33. A clothespin shaped hole 50 and slit 52 in the fixed end 35thereof are adapted to be slipped over the wire clip 36. The wire clip36, shown in FIG. 5, is generally C-shaped and adapted to fit within andwrap about the circumference of the groove 56 extending across thebottom opening 58 illustrated in FIG. 4. The bottom opening 58 receivesthe end of the lever 34 which snaps onto the C-shaped ring 36 by actionof the groove 52. The shape and springiness of the C-shaped clip 56retains it in position once the clip's free ends 37, 39 are snapped intothe groove 56 and holes 59 in groove 56 on each side of housing 30.Similarly, the lever 34 is snapped into place so that hole 50 fitsaround the exposed portion of the wire clip 36 traversing the bottomopening 58 of housing 30.

The top opening 42 in housing 30 extends a distance sufficient toprovide the desired degree of movement of the lever 34 and pull wire 12with regard to the tubular member 10.

Referring now to FIG. 7, perspective view of the slideable member 32illustrates the opening 44 for receiving the free end 37 of the lever 34and moving it back and forth within the opening 42 of the housing 30 aswell as an opening 60 within which the other end of the lever 34 isaccommodated in the assembly depicted in FIGS. 2 and 3.

Preferably, the inside diameter 62 of the slideable member 32 isundersized somewhat with respect to the outside diameter of the housing30 so that friction may be relied upon to hold the slideable member inany position depicted in FIGS. 1 to 3 while the lead and stylet assemblyis advanced, withdrawn or rotated by the physician in manipulating theposition of the distal end of the catheter or lead.

Turning now to FIGS. 8 to 13, first and second preferred embodiments ofthe distal portion 16 of the stylet assembly depicted in FIG. 1 areillustrated. In these embodiments, it is anticipated that tubular member10 is constructed of hypodermic needle tubing, such as 304W stainlesssteel tubing having an outside diameter in the range of 0.012 to 0.016inches with about 0.0035 inch wall thicknesses. The pull wire ispreferably 0.005-0.007 inch stainless steel wire of high tensilestrength.

The first preferred embodiment of forming the first and second openings18 and 20 and the treatment of the predetermined length of tubularmember 10 extending therebetween is illustrated in FIGS. 8 to 11. Inthis embodiment, the predetermined length of the tubular member 10 isflattened between the openings 18 and 20 to provide a predetermined biasto curve away from the length of wire 12 as it is drawn taut between theopenings 18 and 20. The flattening also renders the tubing in theflattened section more resistant to kinking and better able to flex tovirtually a full 180 degrees.

The distal portion 16 illustrated in FIG. 8 includes the first andsecond openings 18 and 20, the distal tip 22 and the length of wire 12extending from its point of attachment 23 made in the distal tip 22 outthe second opening 20, alongside the flattened predetermined length 11and back into the lumen 13 through the first opening 18.

Turning now to FIGS. 9 and 10, they illustrate cross sectional views ofthe tubular member 10 and pull wire 12 taken along section lines A--Aand B--B, respectively. In FIG. 9, the pull wire 12 is shown residingwithin the lumen 13 of the tubular member 10. In FIG. 11, the wire 12 isdepicted extending from the opening 18 in the tubular member 10 anddistally along the flattened surface 11 of the tubular member 10 at thepoint where the section B---B was taken in FIG. 8. The original lumen 13in that section is compressed substantially.

Turning now to FIG. 11, it depicts a simple die for flattening section11 of the distal portion 16 by placing that portion of the tube 10 in agroove 70 in the elongated block 72, fitting an elongated hardened steelpin 74 on top of the tubular member 10 within groove 70 and applyingforce in the direction of the arrow 76 to flatten the tubular member.Preferably the width of the groove 70 is selected to be slightly largerthan the outside diameter of the tubular member 10.

This section of this steerable stylet that actually produces the dynamiccurvature is strengthened and stiffened by flattening the tube ratherthan removing metal or cutting an elongated window. The alternativemanner in which an elongated opening may be obtained and an alternativemanner of coupling the distal end of the tubular member 10 and the pullwire 12 are depicted in FIGS. 12 and 13.

FIGS. 12 and 13 are top and side views of the distal portion 16 of thesteerable stylet assembly wherein the two openings 18 to 20 and theflattened section 11 are replaced by an elongated cutaway portion of thetube 10. The elongated cutaway portion depicted in FIGS. 12 and 13 isillustrated in the same fashion as FIGS. 8 to 11 in that the first andsecond openings 18 and 20 are replaced by first and second cuts 18' and20' and the elongated flattened portion 11 is replaced by the cutawayportion 11'.

There is no fixed attachment of the pull wire to the distal end 22 ofthe tubular member 10 depicted in FIGS. 12 and 13. Instead, the pullwire 10 is adapted to terminate in ball shaped element 23 having adiameter greater than the inside diameter of the lumen 13. Thisconstruction allows the same traction forces to be applied as in thefixed end embodiment illustrated in FIGS. 8 to 10. It also allows forthe advantageous use of a rounded end or ball-tip stylet which mayreduce perforations of the lumen of the lead body or the thin wallcatheter that may be employed with the stylet assembly. Alternative tipdesigns may be provided to act as keys to engage with active fixationelements which may be rotated out of or extended from the distal end ofan active fixation pacing lead in the manner described in the abovereferenced '013 patent, for example.

In constructing prototypes of the steerable stylet of the presentinvention, it was found that the cutaway tubing embodiment of FIGS. 12and 13 was inferior to the flattened embodiment of FIGS. 8 to 11 inresistance to kinking. It has also been found that the flattenedembodiment is easier to manufacture than the cutaway embodiment. In thecourse of experimentation, an attempt was also made to fabricate asteerable stylet merely having the first and second spaced apartopenings 18 and 20 in the tubular lead body without either cutting awaya portion of the body or deforming that portion between the twoopenings. Experiments conducted with the pull wire extending outside thetube between the first and second openings and fixedly attached at thedistal end thereof showed an unacceptable tendency of the tube to kinkat even moderate curvatures. Consequently, there is presently a beliefthat the embodiment of FIGS. 8 to 11 with either the distal end of thepull wire 10 crimped to or engaged with the distal end 22 of the tubularmember 10 is preferred to the embodiment of FIGS. 12 and 13 or theunmodified tubular embodiment.

Turning now to FIG. 14, it is an illustration of the dynamic curvaturein the X-Y plane imparted by a prototype steerable stylet andmanipulative handle assembly in accordance with the teachings of thepresent invention. In FIG. 14, the origin of coordinates is thebeginning of the deflectable part of the stylet tubular member 10, andthe illustrated points (shown by the rectangles) represent thecoordinates of the tip 22 at various states of deflection for a styletwith a predetermined distance of 2.5 inches for the extra-lumenal wire12. The curve represents the locus of all points through which the tipwill pass as the stylet is dynamically deflected and illustrates thatthe stylet tip 22 may be deflected from straight at point 100 to point102 where it forms a complete circular loop.

The steerable stylet and manipulative handle assembly described above inconjunction with its preferred embodiment provides the desirablefeatures of stiffness, torque transmission, and dynamic curvature forthe range of curvatures desired in use as illustrated in FIG. 14 withreasonable force and high resistance to kinks. In any given implantprocedure, the ability to provide dynamic curvature changes avoidswithdrawing the stylet to change its curvature as the lead is passed.The one-handed manipulation of the handle facilitates the achievement ofdynamic curvature while advancing and rotating the lead or catheter. Inanimal tests, it was found that the dynamic curvature facilitated thelocating and passage of the distal portion of a pacing lead into thecoronary sinus with unaccustomed ease.

The embodiments as described include only a single flattened or cutawayportion of the tubular member 10 and the pull wire 12 extending thepredetermined distance extra-lumenally thereby. It will be understoodthat in certain applications, it may be desirable to provide for afurther or a series of further replications thereof along the length ofthe stylet.

As many apparently widely different embodiments of the present inventioncan be made without departing from the spirit and scope thereof, it isto be understood that the invention is not limited to the specificembodiments thereof except as defined in the appended claims.

What is claimed is:
 1. A stylet and manipulative handle assemblycontrollable to form selected curvatures in a distal portion of acatheter or lead having a lumen extending therethrough comprising:aflexible, elongated tubular member having proximal and distal ends andproximal and distal portions thereof and having an internal axiallydisposed lumen; at least one traction element extending through saidlumen and attached to said distal end portion of said tubular member, atleast a portion of said traction element eccentrically guided outsideand parallel to said tubular member for a distance along said tubularmember, said traction element having a proximal end projecting from anopening in said proximal portion of said tubular member; andmanipulative handle means attached to said proximal portion of saidtubular member and to the proximal end of said traction element forexerting tension on said traction element to form the said tubularelement to a desired degree of curvature depending upon the amount oftension and whereby said catheter or lead is similarly curved: andwherein said manipulative handle comprises:a longitudinal housing havinga distal end thereof attached to said proximal end of said tubularelement and receiving said proximal end of said traction elementtherewithin; a reciprocating hinge lever coupled for pivotal motion withrespect to said longitudinal housing and adapted to be disposedtransversely therewithin; means for attaching said proximal end of saidtraction element to said lever; and slide means coupled to said leverand adapted to slide upon said longitudinal housing for advancing andretracting a free end of said lever and thereby releasing and applyingtraction to said traction element to release or induce curvature in thedistal portion of said elongated flexible tubular member.
 2. Theassembly of claim 1 wherein said elongated tubular member has a selectedprofile coextensive with said distance along said tubular member fordecreasing the tendency of the tubular member to kink when curved out bythe application of traction to said traction element.
 3. The assembly ofclaim 2 wherein said profile is a region of reduced cross sectioneffected by compressing said tubular element upon itself.
 4. Theassembly of claim 2 wherein said profile is effected by cutting away oneside of said tubular member.
 5. A stylet and manipulative handleassembly controllable to form selected curvatures in the distal portionof a catheter or lead having a lumen extending therethrough,comprising:a flexible, elongated tubular member having proximal anddistal portions thereof and having an internal axially disposed lumen;at least one traction element extending through said lumen and attachedto said distal portion of said tubular member and having a proximal endprojecting from said proximal portion of said tubular member, at least aportion of said traction element outside said tubular member for adistance along said tubular member; and manipulative handle attached tosaid proximal portion of said tubular member and to said proximal end ofsaid traction element for exerting tension on said traction element atsaid proximal end to form the said tubular element to a desired degreeof curvature depending upon the amount of tension and whereby saiddistal portion of said catheter or lead is similarly curved, whereinsaid manipulative handle comprises:a longitudinal housing having adistal end thereof attached to said proximal end of said tubular elementand receiving said proximal end of said traction element therewithin; areciprocating hinge lever coupled for pivotal motion with respect tosaid longitudinal housing and adapted to be disposed transverselytherewithin; means for attaching said proximal end of said tractionelement to said lever; and slide means coupled to said lever and adaptedto slide upon said longitudinal housing for advancing and retracting afree end of said lever and thereby releasing and applying traction tosaid traction element to release or induce curvature in the distalportion of said elongated flexible tubular member.
 6. A stylet andmanipulative handle assembly for insertion into the proximal opening inthe lumen of a hollow elongated catheter or lead body for imparting acurvature in a portion thereof and enabling the rotation thereof bymanipulation of the handle at the proximal end of the elongated catheteror lead body, said stylet assembly comprising:a two piece stylet adaptedto be inserted into said proximal opening and through the length of saidlumen, said stylet comprising; an elongated hollow tubular member havingproximal and distal ends and portions and at least one opening in theside thereof; a length of pull wire extending within the tubular memberthrough a proximal opening therein and through said side opening andextending outside the tubular member for a predetermined distance, aportion of said tubular member extending along said predetermineddistance being compressed upon itself such that said tubular member isflattened only along the side of said side opening; and means forengaging the distal end of said pull wire with the distal end of saidtubular member, so that traction applied proximally on said pull wiretends to induce a curvature in said tubular member; and manipulativehandle means coupled to the proximal end of said tubular member andreceiving said pull wire further comprising means for applying tractionto said pull wire in said proximal direction to induce a curvature insaid hollow tubular member.
 7. The assembly of claim 6 wherein saidtubular member further comprises:a second side opening adjacent to thedistal tip thereof and located said predetermined distance from saidfirst opening and wherein: said pull wire extending outside said distalportion of said tubular member is threaded into said second opening and;said engaging means is adapted to mechanically couple the distal ends ofsaid pull wire and said tubular member together.
 8. The stylet assemblyof claim 6 or claim 7 wherein said manipulative handle means furthercomprises:an elongated tubular housing having a necked down portion withan axially disposed opening in said necked down portion for receivingsaid proximal end of said elongated tubular member and the proximalportion of said pull wire of said stylet therein; a thumb actuableslidable member disposed around at least a portion of the length of saidtubular housing; moveable lever means having a predetermined lengthadapted to being pivotally coupled at one end to said housing and at theother end to said slidable member; and means for attaching said pullwire to said moveable lever for applying traction thereto upon proximalmovement of said slidable member and said other end of said lever inrelation to said housing.